The invention relates to a device for ultrasonic inspection of the weld seam of longitudinally welded pipes—in particular large pipes, for longitudinal and transverse flaws according to the preamble of claim 1.
A device for ultrasonic testing of longitudinal weld seams for longitudinal and transverse flaws has been published by Scott Lebsack and Helmut Heckhauser in the magazine “Materials Evaluation” (August 1995, pages 886-891), entitled “Immersion Probe Arrays for Rapid Pipeline Weld Inspection”. Included here is a holding system in which two test head systems are mounted. Each test head system includes four test heads to inspect for longitudinal flaws and a test head to inspect for transverse flaws. The two test head systems for longitudinal flaw inspection are positioned to the right and left next to the weld seam. The test head for transverse flaw inspection extends slantingly at an angle of about 45° in relation to the weld seam. The oscillators in the test heads are round with a diameter of 5 mm. The test head systems operating in immersion technique is provided with connections for the coupling medium.
DE 198 26 759 C1 discloses a device for ultrasonic testing of longitudinal weld seams for transverse flaws. This known device includes at least one test head which is arranged in a holder element and extends in line with the weld seam and which is provided with an oscillator. The test head is provided with at least one coupling medium connection having a channel ending in the area of the oscillator. Disposed in the test head is a broad rectangular oscillator having a width extending transversely to the weld seam. The channel carrying the coupling medium is shaped in the form of a nozzle in the outlet area and has an opening transverse to the weld seam in correspondence to the width of the rectangular oscillator. The outlet zone of the nozzle is adjusted to the weld seam elevation. The respective nozzle element is connected with the housing by means of long screws which traverse the housing accommodating the test head.
The inspection for transverse flaws includes, preferably, two test heads in tandem disposition. The tandem disposition is suited to different thicknesses of the pipe being tested by fixedly securing one test head on a test carriage and arranging the second test head in a manner to be able to move axially in relation thereto.
The conventional devices have the drawback that the adaptation to greatly varying pipe sizes is difficult and complicated to implement and that there are also problems in connection with adjusting the angle of sound incidence in a reproducible manner. Maintenance works involving replacement of damaged parts are also time-consuming.